This relates generally to transmission of data in high voltage systems, and more particularly to galvanic isolation devices for the transmission of data.
Galvanic isolation is a principle of isolating functional sections of electrical systems to prevent current flow from one section to another. In order to prevent current flow, no direct conduction path is permitted. Energy or information can still be exchanged between the sections by other means, such as capacitance, induction, or electromagnetic waves, or by optical, acoustic, or mechanical means.
Galvanic isolation may be used where two or more electric circuits must communicate, but their grounds may be at different potentials. It is an effective method of breaking ground loops by preventing unwanted current from flowing between two units sharing a ground conductor. Galvanic isolation is also used for safety, preventing accidental current from reaching ground through a person's body.
Integrated, capacitive-based, galvanic isolators allow information to be transmitted between nodes of a system at different voltage levels using a high voltage (HV) capacitive barrier along with a differential transmitter and receiver on either side of that barrier. The HV capacitors may be integrated as discrete capacitors, or combined within the transmitter and receiver integrated circuits. In the latter case, each integrated circuit (IC) has a HV capacitor constructed in the IMD (inter-metal dielectric) layers that form the top layers of each IC. HV capacitors are typically implemented on each IC within a single package and connected by bond wires to create a composite capacitor formed from two series capacitors elements. This redundancy provides an increased level of safety, because even if one cap fails, a second capacitor provides isolation.